This invention relates generally to the field of telephone communications, and more particularly to a variety of solid state switches to be used as series elements in telephone lines between the telephone central office and the subscribers.
In the past, many solid state switches have been designed and applied in the various fields using relays, darlingtons, or bipolar transistors. However, these switches are not desirable for telecommunications because they require heavy base currents to keep them "on" or a power source to actuate them. If a remote power source is required, then electrical service must be provided within the customer's house at the point of network line termination. Darlington switches may be used to reduce the above-referenced base current requirement, but there is a large voltage drop across a Darlington solid state switch. These solutions are not acceptable, especially where the subscriber is at a distance away from the central office. Due to the long loop length and large voltage drop in the line, a solid state switch would normally add undesirable voltage drop to the already low current made available for the talk circuit.